Most piping installations require changes of direction. With rigid pipe, the change in direction is effected with elbow-type fittings which attach to lengths of straight pipe. Conventional pipe elbows are available in fixed angular increments, typically 1/8 bend increments (90, 45, 221/2 degrees). When a pipe layout requires an intermediate angular displacement, the pipe fitter finds himself in a difficult situation.
In some specific situations, provision is made for selecting a specific angular displacement. For example, U.S. Pat. No. 2,654,619 to Guam, describes a reducing elbow for welded pipe, part of which has constant radius of curvature and diameter. The pipe fitter can sever the elbow at the desired point and weld it into his run of pipe. Two cuts are required to be made exactly perpendicular to the axis of curvature to provide a weldable fit to the mating piece of pipe. Williams U.S. Pat. No. 2,449,265 provides a rubber automobile radiator hose which can be cut along lines marked to agree with specific automobile models. The hose depends on its elasticity at the cut end for attachment to the car radiator.
A need therefore exists for a pipe elbow which can be adapted to whatever angular displacement is required for a piping installation, and it is this need which the invention addresses.